﻿using System.Collections.Generic;
using System.Linq;
using Bing.Extensions;

namespace Bing.Data.Queries
{
    /// <summary>
    /// 排序生成器
    /// </summary>
    public class OrderByBuilder
    {
        /// <summary>
        /// 排序项列表
        /// </summary>
        private readonly List<OrderByItem> _items;

        /// <summary>
        /// 初始化一个<see cref="OrderByBuilder"/>类型的实例
        /// </summary>
        public OrderByBuilder() => _items = new List<OrderByItem>();

        /// <summary>
        /// 添加排序
        /// </summary>
        /// <param name="name">排序属相</param>
        /// <param name="desc">是否降序</param>
        public void Add(string name, bool desc = false)
        {
            if (string.IsNullOrWhiteSpace(name))
                return;
            _items.Add(new OrderByItem(name, desc));
        }

        /// <summary>
        /// 生成排序字符串
        /// </summary>
        public string Generate() => _items.Select(t => t.Generate()).ToList().Join();
    }
}
